Automatic refrigerating machine



Feb. 14, 1928.

v E. REGGER AUTOMATIC REFRIGERATING MACHINE Filed Deo I 7 M H 5 Patented Feb. 14, 1928.

UNITED STATES EDUARD BEGGER, F ZURICH, SWITZERLAND.

AUTOMATIC REFRIQERATING YIMAGHIIN' E.

Application led December 21, 1923, Serial No.

The present invention relates to improvements in a method for ensuring the lubrication of automatic small refrigerating machines and to an automaticsmall refrigerating` machine for carrying out thismethod.

lVith refrigerating machines of the conipression type it is inevitable that a small quantity of the lubricant" is carried along with the refrigerating medium performing a cycle. This is due to the fact that the lubri# cant is partly atomized by the compressor and is then forced in the form of mist, together with the compressed vapours of the refrigerating medium, into the liqueiier from where it passes into the evaporator.

In case the lubricant is insoluble in the refrigerant, it must be prevented as much as possible from getting into the evaporator as it lowers the transmission of heat inv the evaporator on being precipitated on the walls of the latter. Soluble lubricants on thc contrary do not cause an essential lowering of 'lil the transmission of heat in the evaporator. Such lubricants may be permitted to get into the evaporator. lVith refrigerating machines which work automatically and are totally enclosed (i. e. are notprovided with stuiiing boxes), the lubricant (which for sake of simplification shall be called hereinafter oil) must be returned into the compressor because otherwise the lubrication fails after some time. A return of the oil dissolved in the refrigerating medium from the evaporator into the casing of the compressor is, however, dificultand, at all events, is only possible wlien the compressor works according to the wet method, that is to say when liquid particles are drawn into the compressor together with the vapors. If, however', the percentage of oil in the mixture contained in the compressor be small, then besides vapor-v ous refrigerating medium also a considerable quantity of liquid refrigerating medium must be drawn by the compressor in order to return quite a small quantity of oil to the compressor. It is a known fact that by this method of operating the amount of cold produced by the refrigerating machine is con# siderably lowered.

If a refrigerating machine is overiilled, i. e. if such a quantity of refrigerating mediumvis present in the evaporator thatduring thek working, a larger quantity of liquid refrigerating medium together with refrigera-ting medium in 'a gaseous state is drawn continually into the compressor, the machine 682,014, and in Switzerland December 23, 1922.

works also ineiciently. By a skilled attendance an overlilling may of coui'se be avoided. However, with small refrigerating machines used in the household a skilled attendance cannot be expected and therefore an over.- iilling with refrigerating medium occurs in most cases.

The present invention relates now to a method for ensuring the lubrication of automatically Workinosmall refrigerating machines and to a refrigerating machine for carrying out the method which renders possible an economic Working also in the case when the machine is overfilled. According to the invention refrigerating medium and alubricant soluble in the former are introduced into the refrigerat-ing machine in such respective quantities that immediately or at least after a. certain time of working a mixtureof liquid refrigerating medium and of lubricant is formed in the evaporator which .contains atleast of lubricant dissolved in the liquid refrigerating medium. With the small refrigerating machine -serving to carry into eEect this method and having a suction tube interposed between evaporator and compi-essor the suctiontube is, according to the invention, designed partly as a heat exchange device passing through the liquid containing space of the liquefier, anda displacement chamber is interposed between a pressure reducing device and an evaporating space which is in open communication with the displacement chamber.

A constructional example of an automatic enclosed refrigerating machine is illustrated on the accompanyinfr drawings in a vertical longitudinal section iy theaid of which machine the advantages shall be explained which areobtained by the subject matter of the present invention.

On the upper end of a vertical shaft l 'the rotor 2 of an electromotor is fixed and the stator 3 is mounted on a sleeve 4. The shaft 1 drives the compressor consisting of a piston pump 6 arranged Within a cylindrical casing 7 and carrying out an oscillatoryv movement about fulcrum pins 8. 9 denotes a pressure chamber into which the compressor 6 exhausts. 10 is an ascending pipe connecting the chamber 9 with an oil chamber 11 arranged in the upper part of the casing 7 The chamber 1l is in communication with a narrowlannular space 13 by means of a pipe 12, the chamber 13 being deined by the casing of the compressor 7 and a cas- 'of which is ing 5 surrounding the Jformer. The casing 5 is surrounded by a jacket 14 the inner wall provided with helicoidal ribs serving to guide the cooling water present between the parts 5 and 14. In this manner a cooling of the refrigerating chamber 13 is` eiected so that the chamber 13 forms the liqueier. 15 denotes the evaporator of the refrigerating machine, ribs 16 being arranged on the evaporator. The liquetier 13 ends in a chamber 2O in which collects the liquefied refrigerating medium. Within the Chamber 20 a pressure reducing device in the form of a float controlled valve is provided comprising a float 17 and a throttle opening l chamber 20 is coiled. This part 21 acts as heat transmitting means. The liquid containing collecting chamber 20 communicates at 17 a with a displacement chamber 22 which in its turn is in communication with the evaporating chamber 23. The cylinder enclosing the displacement chamber 22 is provided in its lower part with holes 24 the number of which increases towards the bottom and through which this displacement chamber 22 is connected to the annular evaporating chamber 23. Instead of increasing the number of holes 24 towards the lower end the same number of holes may be provided in different .elevations but the diameter of the holes may be increased or the number as well as the diameter of the holes may be increased towards said end. In every case the cross-sectional area of the connection between displacement chamber 22 and evaporating chamber 23 increases towards the bottom.

During the working vapour of the refrigerating medium Ais drawn from the evaporator 15 through the tube 18 into the suction chamber 19 of the compressor. This vapour is compressed in the compressor 6 and is delivered through the pipe 10 to the oil chamber 11 from where it flows through the tube 12 into the liquefier chamber 13 in which the vapours are liqueied. The liquefied refrigerating medium flows to the collecting chamber 2() from where its admission to the displacement chamber 22 is controlled by the pressure reducing device 17 and 17 a. Owing to the vexpansion of the refrigerating medium occurring at 17a, a part of it evaporates immediately whereby so much heat is withdrawn from the refrigerating medium remaining liquid that the latter is cooled down from the temperature present in the collecting chamber 2O to the temperature of the evaporator. The gaseous refrigerating medium collects in the displacement chamber 22 and presses on the level of the liquid collecting in the usual manner therein whereby the liquid is pressed into the evaporating chamber 23 proper wherein it evaporates again and starts anew on the cycle.

If now during continuous Working a small quantity of oil atomized in the compressor 6 is carried continuously by the rerigerating medium into the evaporator 15, the liquid level in the evaporating chamber 23 rises by degrees until it is so near to the suction tube 18 that not vonly vapour, but also particles of the liquid are drawn in. As the percentage of oil in the liquid mixture or solution contained in the evaporator 15 is veryhigh the quantity of the drawn-in liquid mixture, which is necessary to replace the oil lost in the compressor casing 7, is only small so that the cooling eliiciency of the machineis only slightly reduced. This reduction is, moreover, counteracted by the action of the coil part 21 of the suction tubel 18. In this part 21 the liquid refrigerating medium in the mixture of liquid refrigerating medium and oil is evaporated vso that only pure oil and vaporous refrigerating medium are drawn into the compressor 6. Owing to the evaporation taking place in the part 21, a certain amount of heat is drawn from the liquid refrigerating medium collecting in the chamber 20, said amount of heat depending on the quantity of liquid refrigerating medium drawn into the pipe 18. Thus it is possible to control in this way in an overlled machine the liquid level in the displacement chamber 22 as well as in the evaporating chamber 23 and thereby the quantity of oil returned from the evaporator to the compressor. This is attained in the following manner:

As has been mentioned above, a part of the refrio'erating medium coming from the liquid co lect-ing chamber 20 evaporates already on passing through the throttling opening 17a; this part is the greater, the higher the temperature of the refrigerating medium coming from the lquefier is above the boiling temperature. The quantity of gasy flowing in to the displacement chamber 22 is therefore dependent on the temperature in the chamber 20. The pressure in the displacement chamber 22 is raised by the height of the liquid columnV in the evaporating chamber 23; therefore a small difference in temperature between displacement chamber 22 and evaporating chamber 23 will exist.` If the quantity of gas generated in the throttle opening 17a is small,

-the dilerence in pressure and the thereby caused difference 'in temperature between the chambers 22 and 23 will besuiicient to liquefy this quantity of gas; the liquid level in the displacement chamber will then adjust itself to a certain height. As soon as for instance the quantity of gas present in l `7he displacement chamber 22 becomes greater, because the difference in the pressure and temperature between thechambers 22 and 23 is too small to liquefy the quantity of gas formed by the passage through the throttling opening, the liquid level in the displacement chamber22 will be more and more lowered. The holes 24 are then more and more uncovered, so that the gas can escape from the displacement chamber 22 through said :holes into the evaporatng chamber 23. The liquid level in the displacement chamber 22 .is thus dependent on the temperature of the cooling medium in the collecting chamber 20. This temperature is in its turn dependent on the quantity' of liquid refrigerating medium which is drawn through the part 21 of the suct-ion tube 18 serving as heat exchange device. This quantity depends, however,

upon the height of the liquid levels in the evaporator chamber 23 and in the displacement chamber 22. In other words, if in a machine in consequence of its being over'llled much liquid is drawn through the suction tube 18, the refrigerating medium in the collecting chamber 20 is so strongly cooled down that less gas gets into the displacement chamber,the result being that the liquid level in this chamber rises whilst the liquid level in the evaporating chamber 23 drops so that lessliquid or no liquid at all is drawn through the suction tube 18. In this manner an automatic adjustment of the liquid level in the evaporating chamber 23 to a determined height takes place so that only such a quantity of liquid is drawn through the tube 18 as is required in order to return to the compressor 6 the oil coming from the latter, whereby the whole proceeding does not influence in any way the elficiency of the refrigerating machine.

This novel method presents the further advantage that, in case the refrigerating medium is expensive, this expensive substance is partly replaced by the cheaper lubricant.

The mixture does not need to be introduced' as such into the refrigerating machine previous to the first starting up of the latter. The required quantity of oil may be filled into a space 11 and the required quantity of refrigerating medium may be filled into the evaporator 15, whereby the suitably chosen quantities of these liquids mix after a certain time of working so that in the evaporator a percentage of oil amounting to at least 30% forms itself automatically.

-I claim:

1. The method of ensuring lubrication of automatic refrigerating machines having a compressor and an evaporator, which comprises charging such a machine with refrigerant and a lubricant soluble therein, removing solution from the evaporator, when the normal liquid level of the refrigerant rises in the evaporator, by suction produced by the compressor, and evaporating refrigerant from the solution during such removal, and supplying the resultant vapor to the compressor..

2. The method of ensuring lubrication of automatic refrigerating machines having a compressor, an evaporator, and a casing incloslng the compressor and an oil chamber, which comprises charging such a machine with refrigerant and a lubricant soluble therein, removing solution from the evaporator by the suction action of the compressor when the normal liquid level in the evaporator rises, and evaporating refrigerant durmg such removal by the heat of the liquid refrigerant condensed, returning the vaporized refrigerant to the compressor and delivering the lubricant sucked in by the compressor mainly into said oil chamber.

3. The method of ensuring the lubrication of automatic refrigerating machines having a compressor and an evaporator, which comprises charging such a machine with refrigerant and at least about thirty percent of a 90 lubricant soluble in the refrigerant to materially increase the volume of the refrigerant when dissolved therein, and withdrawing solution from the evaporator when the normal liquid level in the evaporator rises. 95

4. The method of ensuring the lubrication of automatic refrigerating machines having a compressor and an evaporator, which comprises charging such a machine with refrigerant and at least about thirty percent of an oil soluble in the refrigerant to materially increase the volume of the refrigerant when dissolved therein, and withdrawing solution from the evaporator when the normal liquid level in the evaporator rises.

5. In a refrigeratng machine, a cornpressor, a casing enclosing the same, a condenser in the casing, a displacement. chamber, an evaporator chamber space-1l from and 11o surrounding said displacement chamber and Y communicating therewith near the bottom, means to control the supply o'fliquid refrigerant to the displacement chamber, and a pipe connection from about the normal liquid level in the evaporator chamber to the suction end of said compressor, and heating means for said pipe connection.

6. In a refrigerating machine, a casing,

a compressor therein, a condenser in the casing supplied by condensed refrigerant vapor from said compressor, a collecting chamber arranged to receive liquefied refrigerant, a displacement chamber connected to the collecting chamber, means to control the supply of refrigerant from the collecting chamberA to the displacement chamber, an evaporating chamber connected to and receiving liquid from the displacement chamber, and a pipe connection between the evapber therein, an evaporator arranged belowK the condenser and comprising an internal cylindrical displacement chamber and an external evaporating chamber surrounding said internal chamber and communicating therewith, means for reducing the pressure of the refrigerating medium on its passage from said liquid containing chamber into the internal chamber of the evaporator, a

suction tube interposed between the external chamber of the evaporator and the compressor intake and passing through said collecting chamber, that part of the suction tube passing through the said chamber being a coil for effecting an exchange of heat.

8. In a refrigerating machine in combination, a compressor, a casing enclosing said compressor, a condenser chamber surrounding the casing, and a-liquid collecting chamber therefor, an evaporator arranged below the condenser and comprising an internal cylindrical displacement chamber and an external evaporating chamber surrounding said internal chamber and having communicating connection therewith, the cross-sectional area of the connection between said internal and externa-1 chambersincreasing iu the direction of circulation of the refrigerating medium, a device for reducing the pressure ofthe refrigerating medium on its passage from said collecting chamber into the internal chamber, and a suction tube leading to the suction side othe compressor interposed 'between the external evaporator chamber and the compressor and passing through the collecting chamber of the condenser, that part of the suction tube passing through the collecting chamber being colled for effectlng an exchange of heat.

9. In a refrigerating'machine in combination, a compressor, a casing enclosing said compressor, a condenser chamber surrounding said casing and provided 'with a liquid collecting chamber, an evaporator arranged below the condenser and comprising an interna'l cylindrical displacement chamber and an external evaporating chamber surrounding said internal chamber, the internal chamber having perfor-ations through theV 10. In a refrigerating machine, the combination with a casing and a compressor therein, a condenser chamber surrounding the casing and receiving compressed gas and lubricant, a collecting chamber, an evaporator belowthesame comprising a displacement chamber and an evaporating chamber therein liquid sealed therefrom at the bottom, means to control refrigerant liquid to the displacement chamber, and means controlling the passage of gas between the liquid sealed chambers.l to variable degrees dependent upon the gas pressure in the displacement chamber, and a suction tube between the evaporating chamber and compressor to supply sai-d compressor with mixed refrig- 'erant for compression.

In testimony whereof I affix my signature. u

EDUARD RUEGGER.

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